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AnesthesiaIntermediate

Inferior alveolar nerve block

It numbs the lower teeth on that side, the lip and chin, and almost always the tongue too.
Color anatomical plate: the wall of the mandible was removed to show the inferior alveolar nerve (yellow), the artery (red) and the vein (blue) inside the canal, giving off branches to each root.
Color anatomical plate: the wall of the mandible was removed to show the inferior alveolar nerve (yellow), the artery (red) and the vein (blue) inside the canal, giving off branches to each root.Photo: Old anatomical plate (Siebert) · CC0, Wikimedia Commons

What you need to know

  • The anesthetic is deposited near where the inferior alveolar nerve enters the mandible.
  • It anesthetizes the lower teeth on that side and the bone. Its branch, the mental nerve, exits through the mental foramen (below the premolars) and gives sensation to the lower lip and chin.
  • The lingual nerve is usually blocked too: the anterior two thirds of the tongue and the floor of the mouth go numb.
  • The tooth gets its feeling back before the lip and tongue do: with all local anesthetics, soft tissue anesthesia lasts longer than that of the tooth and bone.
  • While it lasts, the patient may bite their lip or cheek without feeling it, especially children. That's why you have to tell them how long it will last and keep an eye on them.

Terms in plain words

Nerve blockAnesthetic placed near the trunk of a nerve to numb everything that nerve innervates.
Lingual nerveNerve that gives sensation to the front part of the tongue; it runs very close to the inferior alveolar nerve.
Diagram of the inferior alveolar nerve and the lingual nerve
Study diagram · @dra_iswmi

For the exam

Why does the tongue go numb when a lower molar is anesthetized?

Show answerHide answer

Because the lingual nerve runs right next to the inferior alveolar nerve and almost always gets blocked too.

Sources

  1. Powers DB. How To Do an Inferior Alveolar Nerve Block. MSD Manual, Professional Version (2025 revision). View source
  2. American Academy of Pediatric Dentistry (AAPD). Use of Local Anesthesia for Pediatric Dental Patients. Reference Manual of Pediatric Dentistry, 2025:407–14. View source
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